iommu/arm-smmu: Handle stream IDs more dynamically

Rather than assuming fixed worst-case values for stream IDs and SMR
masks, keep track of whatever implemented bits the hardware actually
reports. This also obviates the slightly questionable validation of SMR
fields in isolation - rather than aborting the whole SMMU probe for a
hardware configuration which is still architecturally valid, we can
simply refuse masters later if they try to claim an unrepresentable ID
or mask (which almost certainly implies a DT error anyway).

Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 4b1c87e947fdbc5616314d4d32d3ffdd3aec7a5a..f86d7887f69a6f8102729da75f279165764daefa 100644 (file)
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -165,9 +165,7 @@
 #define ARM_SMMU_GR0_SMR(n)            (0x800 + ((n) << 2))
 #define SMR_VALID                      (1 << 31)
 #define SMR_MASK_SHIFT                 16
-#define SMR_MASK_MASK                  0x7fff
 #define SMR_ID_SHIFT                   0
-#define SMR_ID_MASK                    0x7fff
 
 #define ARM_SMMU_GR0_S2CR(n)           (0xc00 + ((n) << 2))
 #define S2CR_CBNDX_SHIFT               0
@@ -346,6 +344,8 @@ struct arm_smmu_device {
        atomic_t                        irptndx;
 
        u32                             num_mapping_groups;
+       u16                             streamid_mask;
+       u16                             smr_mask_mask;
        DECLARE_BITMAP(smr_map, ARM_SMMU_MAX_SMRS);
 
        unsigned long                   va_size;
@@ -1715,39 +1715,40 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
                dev_notice(smmu->dev,
                           "\t(IDR0.CTTW overridden by dma-coherent property)\n");
 
+       /* Max. number of entries we have for stream matching/indexing */
+       size = 1 << ((id >> ID0_NUMSIDB_SHIFT) & ID0_NUMSIDB_MASK);
+       smmu->streamid_mask = size - 1;
        if (id & ID0_SMS) {
-               u32 smr, sid, mask;
+               u32 smr;
 
                smmu->features |= ARM_SMMU_FEAT_STREAM_MATCH;
-               smmu->num_mapping_groups = (id >> ID0_NUMSMRG_SHIFT) &
-                                          ID0_NUMSMRG_MASK;
-               if (smmu->num_mapping_groups == 0) {
+               size = (id >> ID0_NUMSMRG_SHIFT) & ID0_NUMSMRG_MASK;
+               if (size == 0) {
                        dev_err(smmu->dev,
                                "stream-matching supported, but no SMRs present!\n");
                        return -ENODEV;
                }
 
-               smr = SMR_MASK_MASK << SMR_MASK_SHIFT;
-               smr |= (SMR_ID_MASK << SMR_ID_SHIFT);
+               /*
+                * SMR.ID bits may not be preserved if the corresponding MASK
+                * bits are set, so check each one separately. We can reject
+                * masters later if they try to claim IDs outside these masks.
+                */
+               smr = smmu->streamid_mask << SMR_ID_SHIFT;
                writel_relaxed(smr, gr0_base + ARM_SMMU_GR0_SMR(0));
                smr = readl_relaxed(gr0_base + ARM_SMMU_GR0_SMR(0));
+               smmu->streamid_mask = smr >> SMR_ID_SHIFT;
 
-               mask = (smr >> SMR_MASK_SHIFT) & SMR_MASK_MASK;
-               sid = (smr >> SMR_ID_SHIFT) & SMR_ID_MASK;
-               if ((mask & sid) != sid) {
-                       dev_err(smmu->dev,
-                               "SMR mask bits (0x%x) insufficient for ID field (0x%x)\n",
-                               mask, sid);
-                       return -ENODEV;
-               }
+               smr = smmu->streamid_mask << SMR_MASK_SHIFT;
+               writel_relaxed(smr, gr0_base + ARM_SMMU_GR0_SMR(0));
+               smr = readl_relaxed(gr0_base + ARM_SMMU_GR0_SMR(0));
+               smmu->smr_mask_mask = smr >> SMR_MASK_SHIFT;
 
                dev_notice(smmu->dev,
-                          "\tstream matching with %u register groups, mask 0x%x",
-                          smmu->num_mapping_groups, mask);
-       } else {
-               smmu->num_mapping_groups = (id >> ID0_NUMSIDB_SHIFT) &
-                                          ID0_NUMSIDB_MASK;
+                          "\tstream matching with %lu register groups, mask 0x%x",
+                          size, smmu->smr_mask_mask);
        }
+       smmu->num_mapping_groups = size;
 
        if (smmu->version < ARM_SMMU_V2 || !(id & ID0_PTFS_NO_AARCH32)) {
                smmu->features |= ARM_SMMU_FEAT_FMT_AARCH32_L;